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Noriko Shiiki

Publications and source records attributed to Noriko Shiiki.

17 recordsLinked to original sources

Skyrme Strings

We construct nontopological string solutions with U(1) Noether charge in the Skyrme model with a pion mass term, and examine their stability by taking linear perturbations. The solution exhibits a critical angular velocity beyond which the configuration energetically prefers to decay by emitting pions. This critical point is observed as a cusp in the relation between energy and charge. We find that the maximum length for the string to be stable is comparable to the size of one skyrmion. Beyond the length, it is unstable to decay. This instability raises the possiblity of dynamical realization of Skyrme strings from monopole strings inside a domain wall.

hep-ph

Skyrme Branes

We obtain static selfgravitating solitonic 3-brane solutions in the Einstein-Skyrme model in 7D. These solitons correspond to a smooth version of the previously discussed cosmic p-brane solutions. We show how the energy momentum tensor of the Skyrme field is able to smooth out the singularities found in the thin wall approximation and falls fast enough with the distance from the core of the object so that asymptotically approaches the flat cosmic p-brane metric.

hep-th

Non-Abelian Global Strings at Chiral Phase Transition

We construct non-Abelian global string solutions in the U(N)_L x U(N)_R linear sigma model. These strings are the most fundamental objects which are expected to form during the chiral phase transitions, because the Abelian eta' string is marginally decomposed into N of them. We point out Nambu-Goldstone modes of CP^{N-1} for breaking of U(N)_V arise around a non-Abelian vortex.

hep-ph

Collective quantization of axially symmetric gravitating B=2 skyrmion

In this paper we perform collective quantization of an axially symmetric skyrmion with baryon number two.The rotational and isorotational modes are quantized to obtain the static properties of a deuteron and other dibaryonic objects such as masses, charge densities, magnetic moments. We discuss how the gravity affects to those observables.

hep-th

Supersymmetric Skyrmions : Numerical Solutions

We consider the ${\cal N}=1$ Skyrme model and obtain supersymmetric skyrmion solutions numerically. The model necessarily contains higher derivative terms and as a result the field equation becomes a fourth-order differential equation. Solving the equation directly leads to runaway solutions as expected in higher derivative theories. We, therefore, apply the perturbation method and show that skyrmion solutions exist upto the second order in the coupling constant.

hep-th

Extended Soliton Solutions in an Effective Action for SU(2) Yang-Mills Theory

The Skyrme-Faddeev-Niemi (SFN) model which is an O(3) $σ$ model in three dimensional space up to fourth-order in the first derivative is regarded as a low-energy effective theory of SU(2) Yang-Mills theory. One can show from the Wilsonian renormalization group argument that the effective action of Yang-Mills theory recovers the SFN in the infrared region. However, the theory contains an additional fourth-order term which destabilizes the soliton solution. We apply the perturbative treatment to the second derivative term in order to exclude (or reduce) the ill behavior of the original action and show that the SFN model with the second derivative term possesses soliton solutions.

hep-th

Regular and Black Hole Solutions in the Einstein-Skyrme Theory with Negative Cosmological Constant

We study spherically symmetric regular and black hole solutions in the Einstein-Skyrme theory with a negative cosmological constant. The Skyrme field configuration depends on the value of the cosmological constant in a similar manner to effectively varying the gravitational constant. We find the maximum value of the cosmological constant above which there exists no solution. The properties of the solutions are discussed in comparison with the asymptotically flat solutions. The stability is investigated in detail by solving the linearly perturbed equation numerically. We show that there exists a critical value of the cosmological constant above which the solution in the branch representing unstable configuration in the asymptotically flat spacetime turns to be linearly stable.

gr-qc

Black Hole Skyrmions with Negative Cosmological Constant

We study spherically symmetric black hole solutions with Skyrme hair in the Einstein-Skyrme theory with a negative cosmological constant. The dependence of the skyrmion field configuration on the cosmological constant is examined. The stability is investigated in detail by solving the linearly perturbed equation numerically. It is shown that there exist linearly stable solutions in the branch which represents unstable configuration in the asymptotically flat spacetime.

gr-qc

Black Holes with Skyrme Hair

This paper is intended to give a review of the recent developments on black holes with Skyrme hair. The Einstein-Skyrme system is known to possess black hole solutions with Skyrme hair. The spherically symmetric black hole skyrmion with B=1 was the first discovered counter example of the no-hair conjecture for black holes. Recently we found the B=2 axially symmetric black hole skyrmion. In this system, the black hole at the center of the skyrmion absorbs the baryon number partially, leaving fractional charge outside the horizon. Therefore the baryon number is no longer conserved. We examine the B=1, 2 black hole solutions in detail in this paper. The model has a natural extension to the gauged version which can describe monopole black hole skyrmions. Callan and Witten discussed the monopole catalysis of proton decay within the Skyrme model. We apply the idea to the Einstein-Maxwell-Skyrme system and obtain monopole black hole skyrmions. Remarkably there exist multi-black hole skyrmion solutions in which the gravitational, electromagnetic, and strong forces between the monopoles are all in balance. The solutions turn out to be stable under spherically symmetric linear perturbations.

gr-qc

Collective Quantisation of a Gravitating Skyrmion

Collective quantisation of a B=1 gravitating skyrmion is described. The rotational and isorotational modes are quantised in the same manner as the skyrmion without gravity. It is shown in this paper how the static properties of nucleons such as masses, charge densities, magnetic moments are modified by the gravitational interaction.

hep-ph

Multi-soliton solutions in the chiral quark soliton model

In this article a series of solutions with higher baryon numbers in the chiral quark soliton model are reported. The chiral quark soliton model is a simple quark model that incorporates the basic features of QCD. The B=2 axially symmetric soliton solution within this model was obtained numerically. For $B \ge 3$, in a series of our papers we obtained $B=3 \sim 9,17$ minimal energy soliton solutions with point-like symmetries and $B=3 \sim 5$ axially symmetric saddle-point solutions, using rational map ansatz constructed for multi-baryon number skyrmions. An interesting property of the solutions is that the symmetry of the background configuration is reflected in the degeneracy of the valence quark spectra. We also confirm the existence of the quark shell structure. The shells consist of the four-fold degenerate ground state and higher levels with various patterns, which are realized by the interplay of two symmetries, $SU(2)_L\times SU(2)_R$ symmetry for the quarks and the symmetries of the chiral fields. To obtain correct physical observable, the quantum corrections are necessary. We shall show the quantum states of the axisymmetric solitons within the collective quantization. Upon quantization, various observable spectra of the chiral solitons are obtained. According to the Finkelstein-Rubinstein constraints, the quantum numbers of the solitons coincide with the physical observations only for B=2 and 4 while B=3 and 5 do not. The SU(3) extension of the B=2 soliton is also studied to predict various strange dibaryon states within this model.

hep-ph

Degeneracy of the quarks, shell structure in the chiral soliton

We obtain multi-soliton solutions with discrete symmetries in the chiral quark soliton model using the rational map ansatz. The solutions exhibit degenerate bound spectra of the quark orbits depending on the background of pion field configurations. It is shown that resultant baryon densities inherit the same discrete symmetries as the chiral fields. Evaluating the radial component of the baryon density, shell-like structure of the valence quark spectra is also observed.

hep-ph

Regular and Black Hole Skyrmions with Axisymmetry

It has been known that a B=2 skyrmion is axially symmetric. We consider the Skyrme model coupled to gravity and obtain static axially symmetric regular and black hole solutions numerically. Computing the energy density of the skyrmion, we discuss the effect of gravity to the energy density and baryon density of the skyrmion.

gr-qc

Axially Symmetric Black Hole Skyrmions

It has been known that a B=2 skyrmion is axially symmetric. We consider the Skyrme model coupled to gravity and obtain static axially symmetric black hole solutions numerically. The black hole skyrmion no longer has integer baryonic charge but has fractional charge outside the horizon as in the spherically symmetric case. Therefore, the solution represents a black hole partially swallowing a deuteron. Recent studies of theories with large extra dimensions suggest an effective Planck scale of order a TeV and thus the deuteron black hole may be produced in the Linear Hadron Collider (LHC) in future.

gr-qc

B=3 Tetrahedrally Symmetric Solitons in the Chiral Quark Soliton Model

In this paper, B=3 soliton solutions with tetrahedral symmetry are obtained numerically in the chiral quark soliton model using the rational map ansatz. The solution exhibits a triply degenerate bound spectrum of the quark orbits in the background of tetrahedrally symmetric pion field configuration. The corresponding baryon density is tetrahedral in shape. Our numerical technique is independent on the baryon number and its application to $B \geq 4$ is straightforward.

hep-ph

Vacuum energy of CP(1) solitons

The vacuum energy of two CP(1) solitons on a torus is computed numerically. A numerical technique for zeta-function regularisation is proposed to remove the divergences of the vacuum energy. After performing the numerical regularisation, we observe the effect of the vacuum energy on the two soliton interactions.

hep-ph

Quantum Mechanics on Moduli Spaces

It has been assumed that it is possible to approximate the interactions of quantized BPS solitons by quantising a dynamical system induced on a moduli space of soliton parameters. General properties of the reduction of quantum systems by a Born-Oppenheimer approximation are described here and applied to sigma models and their moduli spaces in order to learn more about this approximation. New terms arise from the reduction proceedure, some of them geometrical and some of them dynamical in nature. The results are generalised to supersymmetric sigma models, where most of the extra terms vanish.

hep-th